Medical devices with various complex structures are currently being developed, and it may not be possible to visually confirm the effectiveness of cleaning without disassembling or destroying the device. In addition, visual inspection provides only a qualitative assessment of the cleanliness of the device and misses biologically important protein residues such as blood fibrin that are invisible to the naked eye. The Radionuclide Method (RNM) is the best method for evaluating and validating the cleaning process of medical devices with areas that are not directly visible. The use of radiolabels on the test soil enables reliable non-destructive analysis of the amount and location of radioactivity remaining after the cleaning process.